Metal with phosphide case and process of producing same



Patented July 16 1935 METAL WITH PHOSPHIDE CASE AND PROCESS OF PRODUCING SAME Roy B. McCauley, Chicago Heights, 111.

No Drawing. Application Jgne 19, 1933, Serial 15 Claims.

This invention relates to metals or alloys of metals or objects made thereof, treated to any desired depth to form a-protective surface or case, or even throughout their mass, the better to enable them to withstand deteriorating influences of a physical, thermal, chemical or other nature.

The invention is applicable to alloys or metals in the abstract or as commercial materials or commodities; and it also applies with especial advantage to manufactured articles or objects, since in some of its forms it has to do with the application of a reagent or reagents in fused or molten state, and some of its advantages arise from the ease with which such a reagent can, by various procedures, be contacted with the subject metal that is to be treated.

The invention resides in the method'of converting the whole or any desired portionof the mass of the subject metal or alloy or an object made therefrom, into a constituency that will render it more resistant to deteriorating influences of the kind hereinbefore mentioned. It also resides in a metal, an alloy or a metallic object when so treated.

One identifying characteristic of the invention is that it is realized by causing phosphorus to react upon or enter into solution with some or all of the mass of the metallic subject treated, and thereby convert the subject into phosphide or phosphides; for instance, by submerging the subject in or spraying it with a phosphide in fused state while the subject is in solid state, so that this phosphide may react upon the subject metal or metals as a pyro-chemical reagentl This reagent may be a phosphide of the same metal as that of the subjected body. It may be a phosphide of one of the ingredients of the subjected body when the latter is an alloy. It may be a phosphide of some metal other than that or those which constitute the treated or subjected body, and particularly one which it may be desirable to add to the subjected metal because of some further advantage contributed by its presence 01; at least a metal tolerable therein. The reagent may even be the phosphides of two or more metals, individually advantageous indifferent ways to the subjected metal. Some of the considerations which render desirable an additional metal or metals, or their phosphides in solution in the subject metal, are the improvement of strength 'or other physical properties; raising chemical resistance; modifying fusing point; improvement of grain structure; assistance of other metals to enter into solution with the subject metal or alloy as an incident to promotion of the resistance qualities constituting the primary aim of the invention; and others.

In connection with the last-named consideration, it will be understood that when more than one metal phosphide is caused to react upon the subject metal, one or more of these metals may be what I shall herein term a by-metal which has the capacity of so improving the grain dimensions of the metal or'metals of the reagent as to cause them to more readily enter into solution with the subject metal or metals.

Oneobject which comes within the purview of this invention and which may be employed in producing the treated metal or subject which also constitutes a part of the invention, consists in contacting the metallic subject that is to be treated, with the phosphide reagent in any manner that involves fusion of the reagent and facilitates reaction between the reagent and the said subject. This contacting may be localized or partial as by directing a'spray of the molten reagent; by partial submergence of the subject metal in a molten bath of reagent; by dusting on or otherwise adhering the reagent and then directing a fusing flame against the part tobe treated; or by a method allied to the electric or gas welding arts. This treatment may also be complete, as by complete submergence of the subject in a bath which will react internally as well as externally upon an object that is treated; .or completed by prolonged and changing application of the spray, fusing element or other localized influence. In any of these treatments, the reaction may be caused to take place to different depths as may be desired, by regulating the duration of the reaction. Electrical or electrode fusion of a phosphide reagent in the presence of the subject will produce measurably good results; it being a fact that the brief duration of fusion incident to electro-deposition is suflicient to at least. cause, by pyro-chemical reaction, to a useful degree conversion of the outer portion of the subject metal by solution of the reagent therewith and consequent union between the respective case. and metal body. The invention contemplates the use of a wide variety of metals which, by their phosphiding, are suited, when fused, to serve as what I term the reagent; The selection of these may be determined by their efllciency, individually or when alloyed, in resisting certain conditions against which thesubject metal is to be fortified orrenederedimmune; orthey may be selected because of their capacity to lend one or more of the particular properties already enumerated. Selecting a formula for the reagent that will influence the fusing'point of the phosphided reagent, or of a subject metal treated thereby, is desirable to avoid overheating the subject metal -when developing a low fusion case thereon. It

case under the heat of a secondary case applied to the same subject body.

The reagent is used in the form of a phosphide in order that the phosphorus'may be protected by the metal that accompanies it and be applied in molten state. The invention contemplates selecting as the metal that protects the phosphorus of the reagent against dissipation, a metal that will also serve, when in solution in the subjct metal, to counteract frangibilty of the phosphided subject. The portion of this strengthening metal in the reagent will be determined by the depth of the case or conversion of the subject. That is to say, the strengthening metal will be put into solution in the subject only to the extent that may be necessary to avoid depreciation of the strength of the treated metal. 1

The hydrogen sulphide group of elements. which consist of the elements arsenic, antimony, tin, mercury, copper, lead, bismuth and cadmium, or some one, two or more of them, combined with phosphorus would serve well as a phosphide reagent and would, when fused and applied in a molten state to iron or steel and some other metals, convert the outer portion. thereof (for instance, the pure iron or the iron ingredient of the steel) into its phosphide and immunize-it or greatly increase its resistance to corrosion. The depth of the phosphide thus developed will depend on the duration of the process. A mere momentary contacting of the subject metal with molten phosphide reagent will suffice to create a case to a measurably useful degree.

One phosphide reagent expressed within limits of proportions that may be successfully used, is tin from about 5% to about 50%, copper from about 25% to about 93%, and phosphorus from about 2% to about 25%. Such a formula would fuse at around 1000 F. and could. be applied in molten state toiron or an iron object in solid state. It is best applied at a temperature of from 1200 to 1600 F., and would realize results that bring it within the present invention.

An illustration of -a lower fusing alloy, which will cause resistance to attacks by strong acids when applied, for instance, to steel tubes, sheets, etc., is tin from about 20% to about 75%, copper from about 40% to 75%, and phosphorus from about 5% to 10%. This phosphide reagent would fuse at about 900 F. or less, and would react upon iron or steel with effects already-stated. It produces an alloy case of great corrosion resistance, and substantial physical properties and at low cost.

If, to a formula coming within the last mentioned limits, one or more other elements of the hydrogen sulphide group, for instance, bismuth or antimony or both of them, be added in a proportion totaling from 1% to 15%, the melting point of the reagent would be lowered; also .larger proportions of the copper and some other metals of the reacting alloy, would be assisted in entering into solution with the subject metal;

and the physical properties of the subject metalwould be improved. The cost of the reagent alloy would be. low, since the important ingredients of the reagent can be derived from scrap copper or scrap tin which contain the other metals such as bismuth and antimony. v

If desired, the reacting phosphide; or some of its base metals, may be selected from the ammonium sulphide group, consisting of aluminum, zinc, chromium, manganese, iron, cobalt and nickel. An iron-copper-phosphorus reagent might be used to good effect in the pyro-chemical process, the iron being within limits of about 30% to 50%, copper from about to 50%, and

phosphorus from 5% to 25%. A good specific formula for this reagent would be iron about 40%, copper about 35% and phosphorus about 25%.

Another specific pyro-chemical reagent acting with good effect upon iron or steel and selected partly from the hydrogen sulphide group and partly from the ammonium sulphide group, is tin about 35%, copper about 50%, nickel -about 1.88%, chromium about 3.20% and phosphorous about 9.9%. This particular alloy reagent when applied to iron pipe gave good resistance to abrasion, erosion and corrosion, as well as a smooth surface. Other proportions of these same ingredients could be used Within the limits of tin from about 30% to about 70%, copper from about 30% to about 70%, nickel from about 1% to about 5%, chromium from about 1% to about 5%, and phosphorus from about 5% to about 15%.

I desire it to be understood that in making up the molten reagent, the invention contemplates the use of one or a plurality of the metals lead, bismuth, copper, cadmium, mercury, arsenic, antimony and tin; also aluminum, zinc, chromium, manganese, iron, cobalt, nickel, tungsten and molybdenum. Each of these will combine with phosphorus to form phosphide and to prepare a phosphide for application in its molten state to a metal in its solid state. But these various ingreclients do more than this. Some lend to the subject metal luster and color and some lend hardness. Some determine the fusing point of the alloy of which they form a part. Some favor resistance to particular corrosive influences. Still others commend themselves in the matter of keeping the product within permissible costs while furnishing a phosphiding base for the reagent, or lend some one or more of the properties hereinbefore mentioned which are incident to the process.

known principles, any melting temperature beproperly selected mixtures of metals above enumerated--together "with phosphorus, and thus treatment temperatures appropriate to different applications of the invention may beassured.

Arsenic, antimony, mercury, bismuth) cadmi-um and aluminum are metals which, without detracting from the phosphiding function of the reagent or adversely affecting the metal structure but rather with improvement of metal structure in some cases, will have the effect of improving the color or. luster of the metal. Cobalt, manganese, zinc, tungsten, molybdenum, nickel and some others will improve grain structure and promote solubility of coarser grained metals into the treated metal, besides having an effect upon fusing point.

Some examples of the use of my invention as well as of that part of the invention which resides inan article having novel character as a result of the application of the process, will be given here by way of illustration. Black iron sheets of thirty gauge, without preliminary cleaning or pickling, whensubjected to the pyro-chemical reaction of 30% tin and 70% copper phosphide of 15% phosphorus contentin other words, a tin-copper phosphide alloy containing 30% tin, 59.5% copper and 10.5% phosphorusthe procedurebeing carried on at a temperature of 1700 F., will take on a thin, flexible oxidation or corrosion resistant case, united with the sheets through a diffused zone of merger produced by alloying of ingredients and having a surface which is of tin-copper phosphide constituency, and an alloy juncture between the case and the More specifically stated, by application of. 4

sheet which is of tin-copper-iron phosphide; while the material of the sheet under the case will be iron phosphide with its proportion of phosphorus gradually decreasing inward but leaving a foundation of the original metal if the process is not continued too long. Such a cased metal sheet may have other coatings of the same alloy applied to it, since the addition of iron to the case first formed will have raised the melting temperature of the case so that it will not readily dissolve in the bath of the second case. Had the temperature used for applying this first case, as above described, been 1200 instead of 1700 F., a much heavier case would have been obtained, but with less reaction between the case and the sheet material. Hence, the process atfords considerable latitude with respect to the proportion of case to treated body and quality of their union by varying temperatures at which the fused reagent encounters the solid metal that is to be treated. The time required for developing a case such as that above described may be as little as fifteen to twenty seconds and still result in a useful thickness of case, and, of course, it may be much longer if a thicker or deeper case is desired.

Similarly, iron or steel wire may be reacted upon by simply drawing the wire through a molten bath of the pyro-chemical reagent herein described, thereby causing the wire to receive a non-corroding case of such physical strength and inseparably alloyed character that the ends of the wire may be wound tightly upon the body of the wire or upon some other core of small caliber without cracking. scaling or otherwise opening up the case or exposing the body of the wire to corrosive influences. Here, too, the subject metal-in this case the wire-may be treated without preliminary cleaning, scaling or pickling and the procedure, primarily economical as to materials consumed, labor bestowed and apparatus employed, may be rendered still more economical by using the casing bath as an annealing step that will render unnecessary final annealing of the wire-drawing process.

Another example is that of steel tubes, rods, plates and castings, both solid and hollow, upon which may be developed, by analogous application of the pyro-chemical reagent in the molten state to the treated material in the solid state,

the protective phosphide case herein described.

A desirable reagent for the bath in each of the three instances of use or commercial article cited, would be prepared by melting 50% copper phosphide with 50% iron phosphide, the proportion of phosphorus in each being such as to give a copper-iron-phosphide analyzing as about 42.5% copper, 37.0% iron, and 20.5% phosphorus; and this bath would be given a temperature of about 1900 F. and caused to react upon the objects to be treated fora duration of time that would vary according to results desired, but which might be as little as from 20 to 40 seconds.

The formation of a case upon a metal object in accordance with the present invention is entirely different from the coatings of metals such as aluminum, zinc, chromium, tin, lead, copper, nickel, etc., caused to adhere to the metal of the object by fluxes or the like. In the present invention the case is united with the body of the metal by a process which involves the principle of alloying, and even alloying unden conditions that develop a gradual merger from the alloy that forms the case through an alloy which comblues the metal of the object with the alloy of the case and gradually merges into the metal of the object alone, if the process is arrested in time, or having the alloying condition extending throughout the object if this be desired, and phosphorus being always an element of the alloy in a proportion which, to a depth appropriate to the influence that is to be encountered, converts the metal of the object or its case into'the chemically resistant qualities required, Hence, the invention contemplates'not only the method of producing the results described, but a body of metal having a portion of its thickness extending from a surface inward, existing in the form of a phosphide of a metal, and alloyed with the .body of the metal whereby the phosphide portion develops conditions of resistance to external influences while the body of the metal provides physical strength or integrity for the article; also such a body or article in which the phos phided surface portion enters into solution with the adjoining body portion of the object in order to create the alloyed union; also such an article or object in which the alloy gradually changes from that of the outsidesurface or case, through the union between the case and the body, and thence into the body, so that the phosphide of the case gradually disappears through the range of union and the metal of the body gradually increases in proportion until the un-.

serve as an electrode in the process of electric welding, and having this welding rod consist of the phosphide of a metal or metals desired to be deposited upon a metal body by the electric welding process, and the application of which brings into play the phenomenon of fusion of the normally solid body and the electrode at the point of contact; this metallic phosphide welding rod being constructed by any of the formulas herein mentioned in order to lend to the deposited portions thereof the metallurgical formula that may be particularly appropriate in consideration of chemical, physical, electrical or other influences that may be encountered by the work when in use.

I claim:

l. The process of treating metal articles to render them resistant to deteriorating influences, which consists in causing reaction upon the metal of the article while in the solid state by a reagent consisting at least mainly of metal combined with phosphorus and at fusion temperature, and by such reaction alloying metal and phosphorus of the reagent with the metal of the treated article and-converting at least a portion of the metal of the article into its own phosphide.

- 2. The process described in claim 1 in which the metal of the reagent is a difierent metal from that of the article to be treated and the reaction upon the latter produces an alloy of metal phosphides.

has a fusion point materially lower thanthat oi the alloy of metal phosphides produced by the reaction.

4. The process described in claim 1 which also includes depositing upon the metal of the article, a portion of the metal reagent as a coating, and integrally uniting such coating with the article through means of the portion of the reagent which alloys with the metal of the article.

5. The process described in claim 1' in which the reagent is in the form of a metal bath and the extent of its reaction upon the metal of the article is regulated by the duration of subjection of the article to the bath.

6. The process described in claim 1, in which the reacting fused metal phosphide has a fusion point lower than the phosphide of the subjected metal so that it converts a portion of the subjected metal to a phosphide having 'a fusion point that is materially higher than that of the said reacting phosphide, and the converted portion of the subjected metal, while in solid state, is subjected to a second reaction with a molten metal phosphide which increases the phosphide conversion thereof. 1

'7. The process described in claim 1 when the molten reacting metal phosphide includes a plu- -rality of metals at least'one of which physically conditions the metal of the article treated.

8. The process described in claim 1 when the reacting molten metal phosphide includes one or more, grain corrective metals selected from the group consisting of cobalt, manganese, zinc, tungsten, molybdenum, nickel and antimony, and by the resultant grain correction assisting the reagent to enter into alloy with the metal of the article.

9. The process described in claim 1 when the reagent includes phosphide of a metal of the hyphide of a' metal of the ammonium sulphide group.

13. A new article of manufacture, comprising a metal body and a case onsaid body consisting of a phosphide of metal alloyed with a portion of said body and having a diifused zone of union therewith.

14. An article as described in claim 13,111 which i the portion of the body-metal included in the case is phosphided in varying degree that gradually decreases. inwardly. 15. An electrically conductive metal body having a case of greater electrical conductivity than the body consisting of metal phosphide and, alloyed with the portion of the, body which is included in the case.

- ROY B. McCAULEY.

' (S cal) CERTIFICATE or CORRECTION.

Patent No. 2. 007, 978. July 16; 1935,

ROY B. McCAULEY;

It is hereby certified that error appears in the printed specification of the above numhered patent requiring correction as follows: Page 1, second column,

line 40, for "respective". read protective; and that the said Letters Patent should be read with thisiitorrection therein that the same may conform to the record of the. case in the Patent Office.

Signed and sealed this 27m day of'August, A; D. 1935.

Leslie Frazer Acting Commissioner of Patents. 

